Lifting jack



i Sept. 12, H w L K 1,926,712

LIF'TING JACK Filed Feb. '7, 1930 I Patented Sept.

UNITED 1 S ATE -LIFTINGJAC K" Harold W.- Clark, Alliance, assignorto'llhe n Buckeye Jack Manufacturingflompany, V

ance, Ohio, a corporation of Ol iio I l A, z Application Februaryfi,19.30. Serial No."426,544 I Myinvention relates to multiple screwjacksof the type employed forlifting motorcars, al-

' though it is not limited thereto, since" other uses may bemadethereof. Inmy copending application, Serial- No. 322,644,, filedNovember 30,

1928, I have disclosed a lifting jack, of whichthe inafter, to which theimproved results contem-' plated by the invention are largely due.

For a full understanding of the invention, reference is made. to theaccompanying drawing, in which Figure 1 is a top plan view of the jack;Figure 2 is a central vertical section; and Figure 3 is a transversesection along the line III--III of Fig. 2. l

Referring" in detail to the drawing, the, jack of my invention comprisesa one-piece base 10,

having a tubular portion 11 forming a standard. 30 On top of thestandard,a thrust-bearing 12 is positioned, and a nut "13 rests .on thethrustbearing'. A threaded sleeve 14 is supported with in the standard11 by thenut 13. The sleeve .14

post 16 carries a saddlelfia for engaging the structure to be'lifted. ia

The nut 13 is actuated through a cylinder 17, x which is journaled onthe standard 11; gear 18 is secured to the cylinder 17 and'is adapt- 7ed to be driven by a beveled pinion 19, which is journaled in a barrel20 integral with the baselO. The pinion 19 has a shaft portion 21including a socket 22 for the reception of an'operating crank. Asplitring 23, cooperates with a groove in the shaft portion 21 to retainthe pinion in position. a u a i In order to elevate the jack, a suitablyformed crank is inserted in the socket 22 and the pinion the cylinder17, andv nut 13. In order that r'ota-. tion of the nut 13 cause theelevation of the threaded sleeve 14, I provide means for yieldinglyopposing the rotationiof the sleeve. Radial holes 24 and 25 are formedin the sleeve near its then be forced to rotate together.

ring: reached thelimit'of its movement. The engage-,

' In general, the saddle will engage its load be 19 is rotatedtherebytoturn the ring gear 18, QQ H Sufficient toplievell-trrrotalikewise bedepressed, This operation continues l- T M et gh as meant has a sliding engageme t t phmgers 2 23,} the shaftsoiwhich are drilled to receive, the chdsof the pin 26. A spiral spring 29surrounds the pin and the plunger sha ftsfiand is seated '60 undertheheadsjof the plungers to urge them-into frictional engagement with theinner wall the standard llgflhis wallgissomewhattrough bee causethefbase andfstandardare castinijo'ne piece in-asandrnoldhaving asandcore; @The slight roughness of this surface affords sufficientfrictional engagement with the heads 'of the plungers '2'? and 28 toexert a constant force in opposition to the'rctation of thesleeve 14 inthe standard 11 in either direction. It is to be under stood, however,that this frictional engagement rnay bebvercome by the application ofsufficient torque so that the sleeve 14 is forced to turn within thestandard, despite the friction of the plunger-s vwith the latter.-Unless considerable torque is applied, however, the sleeve willnotrotate relative to the standard. v Rotation of thenut 13 thus causes theelevation-of the sleeve 14 to, partially eirtendthe jack.

Iprovide steps 30 and 31; in the form of half 3 turns of a spiralspring, placedwithin the thread forming' the outer surface of the sleeve14.; The springs 30 and 31 have their ends 'bent so as to enter holesdrilled in the root offthe thread, When the sleeve 14 has been raisedso-that the spring 31 engages the lower face of a nut13, it will beapparent that the sleeve and nut will:

Continued? rotation of thenut l3,therefore, causes the elevation ofthepost'lli Within the sleeve 14. 010-. viously, the. post is carriedupwith the sleeve as the latter 'israised, The elevation-of the jack maythus be continued until the post 16 has ment of the saddle 16a with theobjectto be raisedwill prevent-rotation of the post with the sleeve andthusinsure that the former will be lifted upon rotation ofthe nut andsleeve.

fore the sleeve 14is fully extended. 1

The lowering .of the jack is accomplished by a reversal of the stepshereinabove outlined. The impedance oiiered by the frictional engage-'ment-of the plungers 27 and 28 with the standard tion of thesleeve 14with the nut 13- whenthe latter is reversed- The sleeve will thus belowered and the post, in its extended position, will until the. spring3Q'engagesthe upper surface of,

is rotated by the nut, the post is lowered as long as it is preventedfrom rotating with the sleeve.

.The present'invention is characterized by a simplicity that makespossible the manufacture of the device at a low cost. The complicationsof the internal structure of'thestandard which are found in'earliertypes of jacks areentirely avoided in this form. The interior of thestandard is merely a cored-out cylindrical cavity, which requires nomachining operations. to render it .ready for use.

trol means, comprising the plungers 2'7 and 28,,

The cost'of the impedance con:

is likewise very small, yet it affords an effective means forcontrolling the rotation of the sleeve. While the sleeve is being raisedor lowered, its rotation with the nut is prevented, but as soon as thesleeve has reached movement of its axial movement, it may be rotatedagainst the opposing force, resulting from th e frictional engage- "mentof the plungers withthe standard. I It will be obvious that numerous,modifications in the construction described may be made. One ofthespring's'Bl may for example, 'be omitted a'ndthe axial movement of thesleeve'maybe limited by terminating the screw thread short of theend ofthe sleeve. Other changes may likewise be found desirable, butanysuch'changes that'may be made without departing from the v n 1,926,712the nut,whereupon the'sleeve i4 is locked to the nut l 3'and rotatestherewith. When the sleeve 'means for limiting the rotation of the nutrelative-to the sleeve, and a post threaded in said member butmaintained against rotation therewith.

2. In a jack, a standard, a threaded sleeve reciproca ble therein, a nutfor the sleeve and spring pressed plungers reciprocable on a common pincarried bythe sleeve and frictionally engaging a substantially smoothbore in the standard for yieldably opposing the rotation thereof.

3. A jacl; comprising a standard having a sub:

stantially smooth, cylindrical bore therethrough, I

.a sleeve supported therein, and means for ref straining rotation ofsaid sleeve with a substan-- tially constant force including a springpressed plungercarried onla pin transverse to said sleeve for frictionalengagement with said bore.

' HAROLD W. QLARK.

